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01-27-2013, 06:49 PM   #1
roflbrew
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I use a sintered diffusion stone and pure O2 to aerate the wort prior to pitching and fermentation. I ran some back of the napkin calculations and wanted to check that I'm on the right track with how long I should be aerating:

I'm aiming for 8 ppm (=8mG/L) in a 5 gallon batch (it helped me to work in metric):

8 mg/L in a 18.93 liter batch.

To convert oxygen from mg/L to mL/L I used the following formula: mL/L = mg/L x 0.69978

So:

8mg/L = 8 * 0.69978

= 5.59 mL/L

For a 18.93 L batch, that is equivalent to (5.59 * 18.93) = 106 mL total dissolved oxygen.

If I set my oxygen flow meter to 1 liter per minute, I should be able to achieve the target 106 mL (or 8ppm) in about 6 seconds.

Of course, there's a an assumption here that 100% of the oxygen being introduced ends up dissolved in the solution so I could run it a little longer - but does this sound about right? It sounds a lot lower than most of the recommendations I've read so I wanted to double check. Thanks!

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01-27-2013, 07:14 PM   #2
pdxal
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6 seconds is way off what most homebrewers are doing.
Most people don't have a flow meter on their oxygenation system, so volumes/rates may be hard to come by.
For myself, I use the William's Brewing oxygenation system with wand and 2 micron stone, with a small torch cylinder from the hardware store, and turn it on very low, so there is just a stream of bubbles coming out but no foaming on the surface. I run it for 45-60 seconds for a 5-6 gallon batch.
Hope this helps you.

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01-27-2013, 07:48 PM   #3
day_trippr
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There's a thread that was started within the last 10 days re someone bought a DO meter and was experimenting with both pure O2 injection and the ol' shake 'n' bake with atmospheric O2.

Bottom line, with the O2 injection he was seeing around 10% absorption. So take your 6 seconds times 10 and you'll be in the ball park.

After reading Chris White's Yeast I run a flow-metered .5 lpm through a .5u sintered stainless stone while swirling the wort for 4 minutes, aiming for 12-14% O2 content...

Cheers!

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01-27-2013, 07:53 PM   #4
beerbeerbeer123
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Not trying to be a hijacker but does anyone just use O2 to fill the head space and shake to aerate? If so what do i need besides obviously the o2 tank?

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01-27-2013, 07:58 PM   #5
ktblunden
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Quote:
 Originally Posted by beerbeerbeer123 Not trying to be a hijacker but does anyone just use O2 to fill the head space and shake to aerate? If so what do i need besides obviously the o2 tank?
You need the tank, a regulator, and an air stone to diffuse the O2 into the wort. An air stone is only 15 bucks or so, so to go that far only to skip that would be a little pointless. Pretty sure you won't get near the absorption rate by shaking with O2 in the headspace as you will with a stone.
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01-27-2013, 10:50 PM   #6
roflbrew
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Quote:
 Originally Posted by pdxal 6 seconds is way off what most homebrewers are doing.
I know, right? I've been doing the same as you - 45-60 seconds for a 5-6 gallon batch. But doing that math makes it seem like I'm adding way too much O2... The beer tastes fine thought and that's the most important part!
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01-27-2013, 10:50 PM   #7
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Quote:
 Originally Posted by day_trippr Bottom line, with the O2 injection he was seeing around 10% absorption. So take your 6 seconds times 10 and you'll be in the ball park. After reading Chris White's Yeast I run a flow-metered .5 lpm through a .5u sintered stainless stone while swirling the wort for 4 minutes, aiming for 12-14% O2 content... Cheers!
Thanks! That helps a lot
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01-27-2013, 10:56 PM   #8
roflbrew
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Thanks for the replies!

I'd also add that there doesn't appear to be a lot of consensus on what over-oxygenating might do. On Brew Strong Jamil and John said that it can introduce fusel alcohol and acetaldehyde off flavors. I've also heard that it can cause oxidative damage to yeast cells which could inhibit growth.

Then again Wyeast says you can't add too much oxygen!
"Over-oxygenation is generally not a concern as the yeast will use all available oxygen within 3 to 9 hours of pitching and oxygen will come out of solution during that time as well. Under-oxygenation is a much bigger concern."
http://www.wyeastlab.com/hb_oxygenation.cfm

*confused*

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01-27-2013, 11:09 PM   #9
beerbeerbeer123
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Quote:
 Originally Posted by ktblunden You need the tank, a regulator, and an air stone to diffuse the O2 into the wort. An air stone is only 15 bucks or so, so to go that far only to skip that would be a little pointless. Pretty sure you won't get near the absorption rate by shaking with O2 in the headspace as you will with a stone.
The dudes at wyeast said filling o2 in the head space and shaking for 40 seconds is very effective..I just wanted to know how to get the o2 in the head space
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01-29-2013, 08:40 PM   #10
ptjusa2000
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Is there any point after pitching yeast that oxygenating the beer would be beneficial? What would the benefits be? Could this assist in an underpitched batch? I'm a newbie and these questions are going through my head as I observe my first AG, 5 gal batch ferment from pitching a smack pack with no starter. By all calculations I've underpitched so I'm wondering what my options might be to ensure I hit my target final gravity. Thanks in advance for anyone replying.

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